We are studying the fine structure, synthesis and assemble of the two envelope proteins of Vesicular Stomatitis Virus (VSV) grown in several different animal cell lines in culture. At the same time we are studying the carbohydrate moieties on the VSV glycoprotein (G) on virus grown in normal cells and in several mutant (lectin resistant) CHO cell lines. The latter studies have shown that the genetic defect in the mutant cells is reflected in the oligosaccharide moieties added by the host cell to the virion G protein. We are also studying the en bloc addition of a large mannose 7-9 core to cell and virus glycoproteins and its subsequent trimming to the final core size of mannose 3-4 plus distal sugar residues (gal, GlucNAc, sialic).